In recent years, with the development of information processing technology, various user interfaces for operating a device which performs information processing (hereinafter also referred to as a “user interface (UI)”) have been developed. As such UIs, UIs based on a line of sight of the user, a gesture of the user, or the like are known.
For example, a system in which tracking of the line of sight of the user using a camera and recognition of the gesture of the user using a camera or sensor are performed, and display of an object being viewed by the user is updated on the basis of tracking and recognition results is disclosed in Patent Literature 1.